This disclosure relates to an acid fuel cell system, such as a phosphoric acid electrolyte fuel cell. More particularly, the disclosure relates to a condensing heat exchanger for use in an acid fuel cell system.
One type of acid fuel cell uses a phosphoric acid electrolyte. Typically, a condenser is used in conjunction with the phosphoric acid fuel cell to condense and remove water from a gas stream, such as anode or cathode exhaust. One type of condenser heat exchanger uses multiple tubes supported in multiple fins. A coolant flows through the tubes to condense water from the gas stream flowing between the fins.
The water vapor in the gas stream includes a small amount of phosphoric acid. The heat transfer fins at an upstream portion of the condenser heat exchanger have exhibited corrosion due to acid condensation on the fins. Accordingly, the corrosion products must be removed during a maintenance procedure to prevent the fins from becoming blocked, which could inhibit the gas stream flow through the condenser heat exchanger. Corrosion-resistant metals, such as stainless steel and HASTELLOY, have been used for the fins and tubes. Use of corrosion-resistant metals has not extended the maintenance interval for removing corrosion products from the condenser heat exchanger to a desired duration, which may be ten years or more.
What is needed is a condensing heat exchanger for an acid fuel cell system that has increased corrosion resistance and an extended service life.